//: C04:Effector.cpp
// Jerry Schwarz's "effectors."
#include <cassert>
#include <limits> // For max()
#include <ostream>
#include <sstream>
#include <string>
using namespace std;

// Put out a prefix of a string:
class Fixw {
  string str;

public:
  Fixw(const string &s, int width) : str(s, 0, width) {}
  friend ostream &operator<<(ostream &os, const Fixw &fw) {
    return os << fw.str;
  }
};

// Print a number in binary
typedef unsigned long ulong;
class Bin {
  ulong n;

public:
  Bin(ulong nn) { n = nn; }
  friend ostream &operator<<(ostream &os, const Bin &b) {
    const ulong ULMAX = numeric_limits<ulong>::max();
    ulong bit = ~(ULMAX >> 1); // Top bit set
    while (bit) {
      os << (b.n & bit ? '1' : '0');
      bit >>= 1;
    }
    return os;
  }
};

int main(void) {
  string words = "Things that make us happy, make us wise";
  for (int i = words.size(); --i >= 0;) {
    ostringstream s;
    s << Fixw(words, i);
    assert(s.str() == words.substr(0, i));
  }
  ostringstream xs, ys;
  xs << Bin(0xCAFEBABEUL);
  assert(xs.str() == "1100"
                     "1010"
                     "1110"
                     "1011"
                     "1010"
                     "1011"
                     "1110");
  ys << Bin(0x76543210UL);
  assert(ys.str() == "0111"
                     "0110"
                     "0101"
                     "0100"
                     "0011"
                     "0010"
                     "0001"
                     "0000");
}